Air Pollution Impacts

Lava Beds National Monument

Natural and scenic resources in Lava Beds National Monument (NM) are susceptible to the harmful effects of air pollution. Fine particles, nitrogen, and ozone impact natural resources such as vegetation and wildlife, and visibility of scenic vistas. Click on the tabs below to learn more about air pollutants and their impacts at Lava Beds NM.

Visibility

Nitrogen & Sulfur

Ozone

Human-caused haze and fine particles of air pollution sometimes reduce visibility of scenic vistas like this one at Lava Beds NM, California.

Many visitors come to Lava Beds NM to enjoy vistas of volcanic formations and to experience the remnant Modoc Indian culture. Unfortunately, this scene is sometimes obscured by haze caused by fine particles in the air. Many of the same pollutants that ultimately fall out as nitrogen and sulfur deposition contribute to haze and visibility impairment. Additionally, organic compounds, soot, dust, and wood smoke reduce visibility.

Visibility effects at Lava Beds NM include:

At times, reduced visibility due to human-caused haze and fine particles of air pollution;

Reduction of the average natural visual range from about 150 miles (without the effects of pollution) to about 90 miles because of pollution at the park;

Reduction of the visual range to below 50 miles on high pollution days.

Arid shrublands and other vegetation communities at Lava Beds NM, California, are sensitive to nitrogen deposition and resultant changes in species composition.

Nitrogen (N) and sulfur (S) compounds deposited from air pollution can harm soils and vegetation at Lava Beds NM. N deposition may disrupt soil nutrient cycling and alter plant communities. In some areas of the country increased N deposition has allowed weedy annual grasses to invade shrublands and grasslands, similar to those present at Lava Beds NM. These grasses have replaced native plants that evolved under N-poor conditions. In southern California, increased N deposition has contributed to invasions of annual grasses and increased fire risk in shrublands at Joshua Tree NP (Rao et al. 2010).

Surface waters are also sensitive to N. Surface waters in the monument are limited to a few seeps, however, these seeps provide habitats for species of fern in cave entrances and collapsed structures at the monument that are not found in the surrounding semi-arid landscape. Fern flora in these micro-wetland refuges are remarkable for both species diversity and the number of populations. Ferns are potentially sensitive to eutrophication (enrichment) from N deposition at Lava Beds NM.

N and S deposition can also cause acidification that may harm soils and vegetation. Increased sulfur dioxide and sulfuric acid emissions from geothermal development could harm lichen species sensitive to acidification.

How much nitrogen is too much?

Nitrogen is a fertilizer and some nitrogen is necessary for plants to grow. However, in natural ecosystems, too much nitrogen can disrupt the balance of plant communities, allowing weedy species to grow faster. For example, too much nitrogen causes changes in forest lichen communities, with sensitive species gradually replaced by pollution-tolerant species. The amount of nitrogen that ecosystems can tolerate without significant harm is called the critical load. Critical loads can be used to establish air quality goals for ecosystem protection and management. In California, the critical load for sensitive forest lichen species is about 3.1 kg N/ha/yr (Fenn et al. 2010). Nitrogen deposition can also promote invasive species like cheatgrass, which could be a problem in grasslands like those in Lava Beds NM (Vasquez et al. 2008). N deposition in the area is relatively low (estimated at less than 1 kg/ha/yr), but the potential development of nearby geothermal resources would likely result in increased emissions of nitrogen oxides (and sulfur dioxide) and increased risk to resources.

While foliar ozone injury has not been surveyed at Lava Beds NM, California, there are a few ozone-sensitive species present in the park, such as Populus tremuloides (quaking aspen).

Naturally-occurring ozone in the upper atmosphere absorbs the sun’s harmful ultraviolet rays and helps to protect all life on earth. However, in the lower atmosphere, ozone is an air pollutant, forming when nitrogen oxides from vehicles, power plants, and other sources combine with volatile organic compounds from gasoline, solvents, and vegetation in the presence of sunlight. In addition to causing respiratory problems in people, ozone can injure plants. Ozone enters leaves through pores (stomata), where it can kill plant tissues, causing visible injury, or reduce photosynthesis, growth, and reproduction.